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The Basics of Metabolism



When discussing the basics of metabolism, it is important to first understand that metabolism is the building of large molecules from small molecules and the breaking down of large molecules into small molecules. Living things must build the molecules that carry out cellular functions through anabolic processes, which take in energy. Living things get the energy they need to carry out the functions of life through catabolic processes, which release energy. This energy often takes the form of a molecule called ATP. Other molecules act as electron carriers, which harness the energy released in redox reactions (oxidation-reduction reactions that involve the transfer of charge from one molecule to another) to improve the energy efficiency of metabolic reactions.

At A Glance

  • Metabolism is the means by which living things change molecules, including both anabolic reactions (those that build molecules) and catabolic reactions (those that break down molecules).
  • Energy takes many forms, such as chemical, mechanical, or electrical, and can be transformed from one type to another.
  • Cells carry out chemical reactions that involve energy and enzymes.
  • Metabolic reactions require an input of energy or they produce energy.
  • The biological unit of energy is ATP.
  • Enzymes increase the rate of reactions.
  • The Calvin cycle creates the products plants need using ATP and NADPH.
  • Glycolysis is the first step in cellular respiration.
  • Redox reactions involve the transfer of charge from one molecule to another.